To unlock the 64/128 Ch. recording capacity you have to set the Pro Tools Playback Engine directly to the E3L/E6L Engine.
But if you do so, you aren't able to send Signals to other Devices out of Pro Tools.

This is my use case:
I'm using a S6L at FOH and Mons and they're both sharing the inputs.
The Broadcastmix is fully done in Pro Tools with the same inputs and a S3 faderboard.

I tried to generate a aggregate I/O device for using the S3 AVB outs for my Monitors and also sending the outputs via Dante to the embedder.
This isn't working at all cause Pro Tools needs to have the Engine as Playback Engine, even if you have the "Live Sound Production Toolkit" License on the same Ilock as the Pro Tools license.

Does anyone have a solution for this?

Honestly, I can't understand why there is this restriction even if you have the right license.